Previous work from this laboratory has been focused on surface membrane glycoprotein alterations accompanying tumor virus transformation of tissue culture cells. The future work in this laboratory is aimed at understanding the biological significance of such cell surface alterations. The approach to this problem will be four-fold: Immunological approach - antisera will be prepared against purified glycoproteins, glycopeptides, or surface membranes for use in blocking biological interactions of cells and for helping characterize the glycoprotein from various cell types and cell fractions. Biochemical approach - glycopeptides will be compared as to sugar content, kinetics of synthesis and turnover, release from cells and identity of peptides and glycopeptides from various cells and cell fractions. Genetic approach - using specific antisera, lectins and viruses, mutants defective in some aspect of synthesis of cell surface glycoproteins, will be isolated for use in studying the synthesis and function of these molecules. Biological or functional approach - the effect of antibodies, sugars, and competing glycopeptides on cell-cell interactions, as measured by specific cell adhesion, phase cinematography, or contact inhibition of metabolism will be investigated in transformed cells, control cells and mutant cells. BIBLIOGRAPHIC REFERENCES: Buck, C. A. and Warren, L. The Repair of the surface of animal cells. J. Cell Physiol., in press, 1976. Warren, L. and Buck, C. A. Chemical Changes in Neoplastic Cell Membranes in Membranes and Diseases, edited by L. Bolis, J. F. Hoffman and A. Leaf, Raven Press, New York, 1976.